1. Field of the Invention
The present invention relates to a quality calculator apparatus for use with data decoded by a Viterbi decoder using an encoder tail bit in a convolutional coding system, and more particularly, to a quality calculator apparatus for Viterbi-decoded data that uses zero-state metrics (ZSM) from state metrics obtained through the operation of an add-compare-select unit of the Viterbi decoder.
2. Description of Related Art
In a general communication system, error correction coding is used to keep the level of errors below a predetermined level. This is done by correcting errors caused when a signal passes through a transmission channel contaminated by noise and by other factors which prevent reliable communication. Error correction coding is classified as one of two types: block coding, for adding redundancy corresponding to a block of the data to be transmitted, and convolutional coding, for encoding the sequentially input data according to a generation function of the encoding method. In a communication system adopting convolutional coding, the means for calculating communication quality is very important in reducing the error in determining transmission rate.